1. Field of the Invention
The present invention relates to a management technique of states of a power supply in an image forming system having a plurality of image forming apparatuses.
2. Description of Related Art
There is an image forming system in which two image forming apparatuses are series-connected. In such an image forming system, each of the image forming apparatuses deals with image formation for each side of the same sheet, whereby productivity is increased. Further, it is possible that the upstream one or two image forming apparatuses form an image on a sheet with normal YMCK toners, and another image forming apparatus connected on the downstream side can be used to superpose a transparent color or a special color (other color than YMCK) on the same sheet.
Such an image forming system can be configured by connecting a plurality of normal image forming apparatuses. Then, any one of the image forming apparatuses works as a master apparatus to control the whole image forming system. Further, the other image forming apparatuses works as slave apparatuses, according to the control of the master apparatus.
Note that since the image forming system is made up of a plurality of image forming apparatuses connected, even when an image formation is performed by only one image forming apparatus, power supplies of all the image forming apparatuses need to be in an on-state. In other words, the power supplies of all the image forming apparatuses in the image forming system need to be in the on-state, and the sheet needs to be sequentially conveyed by all the image forming apparatuses of the most upstream side to the most downstream side.
For this purpose, a control is performed such that receiving an instruction of turning on the power supply from the image forming apparatus working as the master apparatus, the power supplies of all the other image forming apparatuses in the image forming system are in tandem turned on. With respect to the management of the state of the power supply of such an image forming system, Japanese Laid-Open Patent Application Publication No. 2007-1175 and Japanese Laid-Open Patent Application Publication No. 2012-56263 give various relevant proposals.
In a normal image forming system made up of a plurality of image forming apparatuses, and in tandem control of on/off of the power supplies of all the image forming apparatuses is performed as described above. Thus, for example, when performing a remote diagnosis in which an image forming apparatus is activated by a communication from outside to read a state of the apparatus, the power supplies of all the image forming apparatuses in the image forming system are set in the on-state even when the state of apparatus of only any one of the image forming apparatuses is read out.
As a result, since the image forming apparatus which does not need to be subjected to the remote diagnosis is in tandem turned on, a problem arises that wasteful power is consumed.
As a management of the state of power supply in the image forming system made up of a plurality of image forming apparatuses, the above Japanese Laid-Open Patent Application Publication No. 2007-1175 proposes a technique in which the whole image forming system is in tandem shifted from a normal power consumption state to a power saving state. This case is a control in which the whole image forming system in tandem operates such that the whole image forming system becomes in the power saving state or the whole image forming system becomes in the normal power consumption state. Thus, such technique cannot deal with the wasteful power consumption, on which the present application focuses, in the image forming apparatus which does not need to be activated.
Further, as a management of the state of power supply in the image forming system made up of a plurality of connected image forming apparatuses, the above Japanese Laid-Open Patent Application Publication No. 2012-56263 proposes a technique in which, depending on image formation (for example, one-side/both-side) modes, (a) the sections of the whole system are powered on in the case of the both-side image forming mode, and (b) all but a part (charge, exposure, development, transfer, fixing, and the like of the image forming section which are not to be used) is powered on in the case of the one-side image forming mode. In this case, the whole image forming system is in a power-on-state, and unnecessary sections are in a state of power saving. That is to say, such technique cannot deal with the wasteful power consumption, on which the present application focuses, in the image forming apparatus which does not need to be activated.